In order to study the characteristics of the different formed free surface vortices at vertical hydraulic intakes, three sets of experiments were conducted. The spiral flow was detected using the Particle Tracking Velocimetry (PTV) measurement technique in three dimensions (3D) by installing two cameras at above and side of the model. The dimensions of model were 2000mm in length, 1300mm in width and 1500mm in height. Through the experiments, extensive data including tangential (Vθ), radial (Vr) and axial (Vz) velocities and their variations with the changing vortex center in different vortex classes, were recorded and analyzed. Using the obtained results, a 3D flow path was drawn for each class of the formed vortex. Moreover, changes in the diameter of the vortex core (Dvo) in the three different classes of vortex were investigated and its changes along the vortex axis were measured. Results showed that the average of Dvo/D (D is the intake diameter) was about 0.14, 0.2 and 0.23 for vortices Class C, B and A, respectively.

Background: The evaluation of treatment-associated errors is important in the radiotherapy process, particularly those resulting related to patient setup.Objective: This research aimed to assess the interfractional setup errors and determine the Clinical Target Volume to Planning Target Volume (CTV to PTV) margin in patients undergoing 3-Dimensional Conformal Radiation Therapy (3DCRT) for head and neck cancer by means of electronic portal imaging device.Material and Methods: In this analytical study, 300 portal images were acquired from 50 patients undergoing 3DCRT for head and neck cancer. Using the portal images of Lateral (LAT) and Antero-Posterior (AP) fields, population systematic (∑) and random (σ) errors were obtained in the lateral, longitudinal, and vertical directions. Finally, based on the International Commission on Radiation Units and Measurements (ICRU) Report 62’s, Stroom’s and Van Herk’s methods, Planning target volume margins were determined.Results: The translational shift ranges were 0-8.1 mm in the ML, 0-9 mm in the SI (AP), 0-8.8 mm in the SI (LAT), and 0-10 mm in the AP directions. The population systematic and random errors were respectively 3.230, 2.753, and 2.997 mm, and 1.476, 1.853, and 1.715 mm in X, Y, and Z directions. The calculated PTV margins using the ICRU-62, Stroom’s, and Van Herk’s formulae were ranging from 3.236-3.551, 6.605-7.493, and 7.932-9.108 mm, respectively. Conclusion: A PTV margin of 7.5-9.5 mm seems safe for ensuring adequate treatment volume coverage. In addition, the EPID is an effective equipment for verifying patient positioning and reducing treatment setup errors.

Background: This study aims to compare the performance of intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) in treating laryngeal cancer.Method: In this retrospective dosimetric study, 15 patients diagnosed with locally advanced laryngeal cancer (LALC) were selected. The dosimetric performance of the two techniques was analyzed using 6 MV X-rays, based on dose-volume histograms for primary and boost planning target volumes (PTVp and PTVb, respectively), relevant organs at risk (OARs), mean Dose (Dmean), maximum Dose (Dmax), 95% Dose (D95), 2% Dose (D2%), 5% Dose (D5%), monitor units per segment (MU/segment), number of MU/cGy, treatment delivery time, along with conformity and homogeneity indices.Results: Both techniques were able to achieve favorable equivalent uniform doses and low doses to OARs. The average total number of monitor units for IMRT was significantly greater than that for VMAT (1724.5 ± 249.5 and 475.3 ± 47.0, respectively for PTVp and 601.4 ± 81.7 and 458.0 ± 62.6, respectively for PTVb). The modulation factor (MU/cGy) of IMRT was significantly greater than that for VMAT for both the primary and the boost phases. The mean treatment delivery time for all cases of IMRT was significantly longer than that of VMAT.Conclusion: The primary distinction between IMRT and VMAT in the treatment of LALC is that VMAT requires significantly fewer monitor units (one-third) compared with IMRT. This reduction contributes to a decrease in treatment time, which in turn positively impacts patient comfort and the accuracy of treatment.

Introduction: We aimed to dosimetrically compare three-dimensional conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT) in terms of planning target volume (PTV) coverage, organ at risk (OAR) sparing, and conformity index (CI). Material and Methods: Planning data of 26 high grade glioma (HGG) patients were used. Prescribed dose for 3D-CRT was 46Gy in 23 fractions to low-risk PTV (LR-PTV) and 14 Gy in 7 fractions to high-risk PTV (HR-PTV). VMAT plans were conducted using 46 Gy in 30 fractions to LR-PTV and 60 Gy in 30 fractions to HR-PTV. Results: Tumor locations were frontal, parietal, temporal, and multi-lobed in 27%, 15%, 23%, and 35% of cases, respectively. Histology was glioblastoma multiform in 89% of patients. Mean values of PTV D95 (dose received by 95% volume) in 3D-CRT and VMAT were 96. 6% and 98. 8% for the LR-PTV and 97. 3% and 99% for HR-PTV (P<0. 001), respectively. Mean values of CI in 3D-CRT were 0. 96 and 0. 97 for LR-PTV and HR-PTV and 0. 98 and 0. 99 for LR-PTV and HR-PTV of VMAT (both P<0. 001), respectively. Mean Dmax of right optic nerve (maximum point dose received by the organ) for 3D-CRT and VMAT were 31. 59 and 25. 57Gy (P=0. 02). Mean Dmax for left optic nerve and optic chiasm were 28. 81 and 22. 14 Gy (P=0. 019) and 42. 24 and 37. 12 Gy (P=0. 055) respectively for 3D-CRT versus VMAT. Doses to other OARs were not statistically different between 3D-CRT and VMAT. Conclusion: VMAT achieved better coverage of the PTV and delivered fewer doses to bilateral optic nerve and chiasm.

The performance of a fish guiding device located just upstream a hydropower plant is scrutinized. The device is designed to redirect surface orientated down-stream migrating fish (smolts) away from the turbines towards a spillway that act as a relatively safe fishway. Particles are added up-stream the device and the fraction particles going to the spillway is measured. A two-frame Particle Tracking Velocimetry algorithm is used to derive the velocity field of the water. The experimental results are compared to simulations with CFD. If the smolts move passively as the particles used in the study the guiding device works very well and some modifications may optimize its performance. In-field Particle Tracking Velocimetry is a suitable technique for the current case and the results compare well with numerical simulations.